Power supply systems are pervasive in many electronic applications from computers to automobiles. Generally, voltages within a power supply system are generated by performing a DC-DC, DC-AC, and/or AC-DC conversion by operating a switch loaded with an inductor or transformer. One class of such systems includes switched mode power supplies (SMPS). An SMPS is usually more efficient than other types of power conversion systems because power conversion is performed by controlled charging and discharging of the inductor or transformer and reduces energy lost due to power dissipation across resistive voltage drops.
Specific topologies for SMPS comprise buck-boost converters and flyback converters, among others. A buck-boost converter typically makes use of an inductor whereas a flyback converter isolates a load and may multiply the voltage conversion ratio through the use of a transformer. In addition to the energy storage element (either inductor or transformer), the operation of the switch is of particular importance, especially in high voltage applications.
One issue that arises with respect to operating semiconductor switches in high voltage environments is avoiding device destruction due to high voltages being applied to the semiconductor switch. Some systems rely on using devices that are specifically designed to withstand high bus voltages encountered in high voltage power supplies. However, even when high voltage devices are used, some design challenges remain with respect to ensuring that devices in the power supply circuit are able to withstand high voltage transient conditions that may arise within the switched-mode power supply. For example, in some switched-mode power supplies, transient voltages within the power supply circuit may exceed the DC or quiescent bus voltages present within the power supply system.